The invention relates to an apparatus for the treatment of board-like articles, particularly printed circuit boards, with a fluid treatment medium, particularly a cleaning, etching, metallizing or rinsing liquid, along a substantially horizontal conveying path, the treatment medium being applied by means of an applicator, particularly a spray, splash or swell nozzle, or by means of a stationary wave to the board surface.
Such apparatuses have been extensively used up to now, particularly for the production of printed circuit boards.
With the increasing integration density of the components on the printed circuit boards, it is necessary to continuously reduce the width of the conductors and the reciprocal conductor spacing. The smaller the dimensions of the conductors, the more important it is to prevent any undercutting of the conductors. Also in connection with various other treatment steps for printed circuit boards, it is becoming increasingly important to allow the treatment medium to act over a precisely controllable time on the surfaces of the boards. With a view to achieving a maximum flow rate the treatment time per board surface also plays a part, so that a minimum board surface treatment time is sought. Simultaneously the treatment result must have a constant quality and it must in particular be ensured that the gaps between the conductors no longer have any residual copper cladding.
These aspects became even more important in connection with the production of multilayer boards, in which the overall board is only obtained after joining together a plurality of individual electronic printed circuit boards and only then can testing for functional characteristics take place. The possibilities of faults are multiplied with the number of layers and simultaneously there in an increase in the damage resulting from the failure of one board.